Security readout for executives and security teams
Plain-English summary
FreeRDP versions before 3.23.0 can read past the end of a small internal array when processing a value sent by an RDP server. The documented impact is limited availability degradation, not data theft or code execution. Organizations using FreeRDP should update, especially where clients connect to servers outside direct administrative control.
Executive priority
Treat as a normal-priority patching item, not an emergency. The vulnerability can be triggered remotely by a server, but sources only document limited availability impact and no known active exploitation. Update FreeRDP during the next standard security maintenance cycle, sooner for users connecting to untrusted RDP servers.
Technical view
CVE-2026-25942 is a CWE-125 out-of-bounds read in FreeRDP’s X11 RAIL handling. `xf_rail_server_execute_result` uses server-controlled `execResult->execResult` to index `error_code_names[]`, which has valid indices 0–6. Values 7 or higher can trigger a global-buffer-overflow read. Fixed in FreeRDP 3.23.0.
Likely exposure
Exposure is limited to FreeRDP versions earlier than 3.23.0. The vulnerable path is in RAIL client handling, with input received from the server. Risk is higher for users connecting FreeRDP clients to untrusted, compromised, or third-party RDP servers.
Exploitation context
The CVE record is not marked KEV, and the provided sources do not state active exploitation. The CVSS vector indicates network reachability, low complexity, no privileges, and no user interaction, but only low availability impact is documented.
Researcher notes
The issue is well-scoped in the advisory and code references: unchecked server-provided index into a seven-element global array. The provided evidence supports the affected range and fixed version. It does not provide proof of broader impact beyond out-of-bounds read or availability degradation.
Mitigation direction
- Upgrade FreeRDP to version 3.23.0 or later.
- Use vendor or distribution packages that include the FreeRDP fix.
- Prioritize clients connecting to untrusted or externally managed RDP servers.
- If immediate upgrade is not possible, review vendor guidance for supported mitigations.
Validation and detection
- Inventory installed FreeRDP versions across workstations, servers, and images.
- Confirm FreeRDP is version 3.23.0 or later.
- Check bundled or statically linked FreeRDP copies in dependent tools.
- Track the GitHub advisory and distro advisories for package-specific status.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-125: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-25942 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.5 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
5.5MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-78q6-67m7-wwf6CVE reference · x_refsource_CONFIRM
- https://github.com/FreeRDP/FreeRDP/commit/9362a0bf8dda04eedbca07d5dfaec1044e67cc6bCVE reference · x_refsource_MISC
- https://github.com/FreeRDP/FreeRDP/blob/3370e30e92a021eb680892dda14d642bc8b8727c/channels/rail/client/rail_orders.c#L75-L76CVE reference · x_refsource_MISC
- https://github.com/FreeRDP/FreeRDP/blob/3370e30e92a021eb680892dda14d642bc8b8727c/client/X11/xf_rail.c#L40-L46CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.